Semiquantitative assessment of 2223/2212 phase homogeneity in Bi(Pb)SrCaCuO superconducting thin films using XRD techniques

Abstract

Phase segregation in multiphasic Bi(Pb)SrCaCuO (BSCCO) films deposited on a silver foil substrate by m metallo-organic decomposition (MOD) has been observed using X-ray diffraction (XRD) techniques. The concept of a phase inhomogeneity factor (PIHF), developed in this work, has been applied to a semiquantitative assessment of the distribution of the 2223 and 2212 phases in the bulk versus film-substrate interface region. On the basis of the XRD-PIHF analyses, we conclude that the silver substrate tends to promote the 2212 to 2223 phase transformation with 2223-rich compositions being formed at the film-substrate interface. This phase transformation was shown to occur at lower temperatures for thinner films. These films contain higher volume-fractions of the 2223 phase and exhibit a higher degree of phase homogeneity. Moreover, the film-substrate interactions seem to induce the lowering of the melting point of the system in the interfacial region and lead to an increase in the degree of c-axis orientation by promoting partial melt textured grain growth.